Method for the transportation of a particulate material at controlled rate

Abstract

The invention provides an efficient method for controlling the flow rate of a particulate material through a pneumatic transportation pipe at a preset value with a high accuracy and rapid response to an external disturbance added to the system by controlling the flow rate of the booster gas. Different from conventional methods in which the flow rate of the booster gas is controlled with the feedforward factor of the variation in the actual flow rate of the particulate material, the inventive method utilizes the variation in the pressure in the receiving unit as the feedback to control the flow rate of the booster gas so that the above mentioned advantages are obtained in the accuracy of control and rapidness of the response to an external disturbance.

What is claimed is: 
     
       1. A method for controlling the rate of pneumatic transportation of a particulate material in a transportaion apparatus equipped with a detector means for detecting the transportation rate of the particulate material in which a pipe for the booster gas is connected to at least one pneumatic pipe for transportation having an end opening at the fluidizing bed in a pressure tank filled with the particulate material and the other end opening at a receiving unit which comprises: calculating the target value of the flow rate of the booster gas through the pneumatic transportation pipe from the pressure difference between the pressure in the pressure tank and the pressure in the receiving unit and the pressure drop corresponding to the target value of the desired transportation rate of the particulate material; and   controlling the flow rate of the booster gas in accordance with the thus calculated value.   
     
     
       2. The method as claimed in claim 1 which further comprises detecting a deviation ΔW of an actual transportation rate of the particulate material WA from a preset value of the desired transportation rate Ws and performing the calculation by replacing the target value of the transportation rate W with (W-ΔW) so as to correct the deviation ΔW. 
     
     
       3. The method as claimed in claim 1 wherein the flow rate of the booster gas is controlled in accordance with an output calculated by use of an equation   Qb=-K.sub.2 W+√(K.sub.2 W).sup.2 +(1/K.sub.1)(Pt-Pb)(2+Pt+Pb)     or     Qb=√K.sub.1 (2+Pt+Pb)(Pt-Pb-K.sub.2 W)     in which Qb is the calculated flow rate of the booster gas in Nm 3  /hour, Pt is the pressure in the pressure tank in kg/cm 2 , Pb is the pressure in the receiving unit in kg/cm 2 , W is the target value of the transportation rate in kg/min and K 1  and K 2  are each a constant determined by the kind of the particulate material under transportation and the dimensional parameters of the pneumatic transportation pipe.